jsp源码实例4（搜索引擎）

package coreservlets;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.net.*;


public class SearchEngines extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
String searchString = request.getParameter("searchString");
if ((searchString == null) //
(searchString.length() == 0)) {
reportProblem(response, "Missing search string.");
return;
}
// The URLEncoder changes spaces to "+" signs and other
// non-alphanumeric characters to "%XY", where XY is the
// hex value of the ASCII (or ISO Latin-1) character.
// Browsers always URL-encode form values, so the
// getParameter method decodes automatically. But since
// we're just passing this on to another server, we need to
// re-encode it.
searchString = URLEncoder.encode(searchString);
String numResults = request.getParameter("numResults");
if ((numResults == null) //
(numResults.equals("0")) //
(numResults.length() == 0)) {
numResults = "10";
}
String searchEngine =
request.getParameter("searchEngine");
if (searchEngine == null) {
reportProblem(response, "Missing search engine name.");
return;
}
SearchSpec[] commonSpecs = SearchSpec.getCommonSpecs();
for(int i=0; i<commonSpecs.length; i++) {
SearchSpec searchSpec = commonSpecs;
if (searchSpec.getName().equals(searchEngine)) {
String url =
searchSpec.makeURL(searchString, numResults);
response.sendRedirect(url);
return;
}
}
reportProblem(response, "Unrecognized search engine.");
}

private void reportProblem(HttpServletResponse response,
String message)
throws IOException {
response.sendError(response.SC_NOT_FOUND,
"<H2>" + message + "</H2>");
}

public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}